1. Field of the Invention
The present invention relates to a method of preventing overlap of multiple personal area networks (PANs).
2. Description of the Related Art
ZigBee is a standard technology for a data network having a low speed transmission rate, low power communication, and high efficiency, and ZigBee is proposed to support convenient use of local communication.
A general ZigBee network generates a single personal area network (PAN) using a connection to a single PAN coordinator (PANC) through a multi-hop. Each PANC has a PAN identity (ID), as its own ID, to distinguish one PAN from another, and has an authority to select or change a radiochannel to be used by the PAN.
A number of radio frequency (RF) channels that the Zigbee network may use is physically limited. As an example, when a band is 2.4 GHz, an available number of the RE channels may be sixteen. Also, an available number of PANs may equal 216 (65536) which is also a maximum number of PAN IDs.
Generally, pluralities of PANs are located relatively far from each other in the ZigBee network, thereby having no difficulty in using a same RF channel. However, a situation where nodes which use the same RF channel are located close to each other may occur due to an expansion of a PAN, a change in the network, and the like.
As described above, a possibility that a node of a PAN does not perform appropriate communication with a neighbor node of the corresponding PAN increases due to RF interference, as a number of nodes of different PANs that use the same RF channel increases. Particularly, since the 2.4 GHz band shares a frequency with an Institute of Electrical and Electronics Engineers (IEEE) 802.15.4 WLAN, there is a possibility of causing interference, in actuality, only three or four channels may be used without interference. In connection with the above, a frequency agility is supported in the ZigBee standard.
However, as a number of nodes that join to the network increases, a coverage of the network is enlarged, and thus, a PAN overlap where multiple PANs overlap with each other occurs. Also, the PAN overlap is worsened due to nodes that are rejoined after disconnection of the network.